IT in Business Enterprise and Personal Communications Networks Lecture – 06

2 Principles of Communications Networks Definition Communication: The sending and receiving of data and information over a communication’s network. Multiuser System: A communications system in which more than one user share hardware, programs, information, people, and procedures.

3 Principles of Communications Networks Role of Communications Networks Communications Network: A set of locations, or nodes, consisting of hardware, programs, and information linked together as a system that transmits and receives data and information. Node: A communication station within a network.

4 Network Service Applications Definition Network Services: The applications available on a communications network. Electronic Mail – Electronic Mailbox: An area of space on magnetic disk in a server or host computer that is allocated for storing an individual’s .

5 Network Service Applications Definition (Continued)

6 Voice Mail: A system that captures, stores, and transmits spoken messages using an ordinary telephone connected to a computer network. – PPTs (post, telephone, and telegraph companies): A general term for telephone companies outside the United States. – Unified Messaging Systems: Offers users the ability to manage several communications media, including telephone, fax, (including those from the Web), and voice mail through a central message manager.

7 Network Service Applications Definition (Continued)

8 Videoconferencing: A type of conferencing in which video cameras and microphones capture the sight and sound of participants for transmission over a network. – Web-casting: Uses the reach of the Internet to link people from anywhere in the world into a conference. Work Group Conferencing: A type of conferencing that uses a software package called groupware to interconnect participants’ computers at their various locations. Participants interact through a microcomputer directly linked to a server and their comments are broadcast to all others taking part in the conference.

9 Network Service Applications Definition (Continued) Electronic Bulletin Board: A network service application that allows messages and announcements to be posted and read. It is accessed by dialing a telephone number and interconnecting with the bulletin board through a modem. Electronic Funds Transfer (EFT): The movement of money over a network.

10 Network Service Applications Definition (Continued)

11 Network Service Applications Definition (Continued) Electronic Data Interchange (EDI): A form of electronic communication that allows trading partners to exchange business transaction data in structured formats that can be processed by application software. Videotex: A two-way, interactive, text-only service operating on mainframe computers that combines a video screen with easy-to-follow instructions.

12 Types of Network Definition Topology: A network configuration, or the arrangement of the nodes or workstations of a network in relation to one another.

13 Types of Network Definition (Continued)

14 Types of Network Wide Area Networks Wide Area Network (WAN): A network that connects sites dispersed across states, countries, or continents. Common Carrier: A company that furnishes public communications facilities for voice and data transmission. T-Carrier: A very high-speed channel designed for use as the backbone of a network and for point-to- point connection of locations.

15 Types of Network Local Area Networks Local Area Network (LAN): A network that interconnects computers and communications devices within an office or series of offices; typically spans a distance of a few hundred feet to several miles. Workstation/Client: A desktop computer connected to a network.

16 Types of Network Local Area Networks (Continued) Server: A computer that hosts a network and provides the resources that are shared on the network. File Server: A computer containing files that are available to all users interconnected on a local area network.

17 Types of Network Local Area Networks (Continued)

18 Types of Network Metropolitan Area Networks Metropolitan Area Network (MAN): A network that transmits data and information over citywide distances and at greater speeds than a LAN.

19 Network Channels Communications Channels Communications Channel/Communications Medium: The physical or cable-less media that link the different components of a network. Physical Channels: – Twisted Pair: A physical communications channel that uses strands of copper wire twisted together in pairs to form a telephone wire. – Coaxial Cable/Co-ax: A physical communications channel that uses one or more central wire conductors surrounded by an insulator and encased in either a wire mesh or metal sheathing.

20 Network Channels Communications Channels (Continued) Physical Channels: – Coaxial Cable/Co-ax: Baseband Cable: Carries a single communication or message at very high megabit speeds, is often used in local area networks. Broadband Cable: Carries multiple signals – data, voice, and video – simultaneously; each signal can be a different speed. – Fiber-optic Cable: A physical communications channel that uses light and glass fibers.

21 Network Channels Communications Channels (Continued) Wireless Channels – Wireless: Wireless channels transmit data using radio signals sent through air or space rather than over wire or optical cables. – Microwave: A cableless medium that uses high-frequency radio signals to send data or information through the air. – Satellite: A cableless medium in which communications are beamed from a microwave station to a communications satellite to orbit above the earth and relayed to other earth stations.

22 Network Channels Communications Channels (Continued) Wireless Channels – Satellite Low-earth-orbit satellite (LEO): Because they circle Earth at a distance far closer than other satellites, LEO satellite systems offer significant advantages: they do not have the comparatively long propagation delays, do not require use of bulky, expensive, directional antennas, less expensive to produce and to launch into orbit. However, greater numbers are needed to provide coverage for a geographic because they do orbit closer to Earth. Very Small Aperture Terminal (VSAT): A satellite earth station with an antenna diameter of under one meter.

23 Network Channels Communications Channels (Continued) Wireless Channels – Infrared: A cableless medium that transmits data and information in coded form by means of an infrared light beamed from one transceiver to another. Transceiver: A combination transmitter and receiver that transmits and receives data and information. – Radio Waves Radio Wave Transmission/Radio Frequency (RF) Transmission: A cableless medium that uses frequencies rented from public radio networks to transmit data and information.

24 Network Channels Communication Channels for WANs and MANs Public Access Networks: A network maintained by common carriers for use by the general public. – Switched Network/Circuit Switched: The complete set of public access networks, so named because the telephone company operates and maintains the switching centers that make it possible to transmit data and information. – Packet Switching: A network communication method in which messages are divided into packets. Each packet is then transmitted individually and can even follow different routes to its destination. – Packet: A piece or section of a transmitted message that contains both data and address information enabling the network to deliver the packet to its intended destination.

25 Network Channels Communication Channels for WANs & MANs (Continued) Private Network: A network made up for leased (dedicated) communications lines. – Leased Line/Dedicated Line: A communications line reserved from a carrier by a company for its exclusive use. Value-added Network (VAN): A public data communications network that provides basic transmission facilities plus enhancements (e.g. temporary data storage and error detection).

26 Network Channels Communications Channels for LANs Backbone Network: A transmission facility designed to move data and information at high speeds.

The End Thank You